An independent Senator is pushing for a parliamentary inquiry to investigate the “complexities” surrounding the Essendon Bombers drugs saga.

John Madigan also said a deeper look into doping in Australian sports was crucial.

Mr Madigan’s push followed an admission by former Bombers coach James Hird that he should have known more about an injections program at Essendon in 2102, that led to the suspension of 34 current and former players.

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“A Senate inquiry is entirely appropriate to try to unravel the onion-layers of complexity surrounding this case,” Mr Madigan said in a statement on Monday.

Last week, the Court of Arbitration for Sport (CAS) upheld an appeal by the World Anti-Doping Authority against an AFL tribunal decision to clear the players of taking the banned substance thymosin-beta 4.

The ‘Essendon 34’ – including 12 current players – were suspended from the sport for 12 months.

Speaking at the Sydney Ethics Centre in an exclusive interview with ABC journalist Tracey Holmes, Hird said there was never any intention to cheat the system, and admitted he should have done more to prevent the situation.

“Firstly, I didn’t oversee the program,” Hird said.

“There was no experimental program that went on.

“There was no intention by anyone, (sports scientist) Stephen Dank included, to cheat the system.

“(But) at certain times I believe protocols weren’t adhered to.”